The solid angle subtended by the periphery of an area `1cm^(2)` at a point situtated symmetrically at a distance of 5 cm from the area is

Options

A. `2xx10^(-2)` steradian
B. `4xx10^(-2)` steradian
C. `6xx10^(-2)` steradian
D. `8xx10^(-2)` steradian

Answer

B

Explanation

Solid angle `dOmega=(dA)/(r^(2))=(1cm^(2))/((5cm)^(2))`
`=4xx10^(-2)` Steradian